Although always a part of philosophy, psychology has close ties as
well
to biology, especially human physiology and medicine. As long as
the mind is in some way attached to a body, this is inevitable.
But,
as you know, it took quite a bit of prying the mind apart from its
religious
connection with an immortal soul before that intimate connection would
be acknowledged!

“The First Physician,” at least as far as the Greeks were concerned,
was Asclepius. He started a partially mystical society or
guild of physicians that was to have an influence for many centuries to
come. During that time, he gained god-like status. Even
Socrates,
as he lay dying of the overdose of hemlock, told his student Crito to
sacrifice
a cock to Asclepius, presumably in thanks for an easy death.

More clearly historical is Acmaeon of Croton (b. 435 bc) in
southern
Italy. A pythagorean by philosophy, he was known for his
anatomical
studies. He is the first person we have record of who dissected
the
eye and discovered the optic nerve. His theory of the mind
included
the idea that the brain is the seat of perception and thought, and that
there are connections from all the sense organs to the brain. He
believed that it was pneuma, meaning breath or animal spirits, ran
through
the body like neural signals.

Disease, he theorized, is at least in part due to a loss of balance
in the body. He postulated a set of opposites, especially hot and
cold, wet and dry, and bitter and sweet, that we need to balance in
order
to maintain health, by controlling our temperature, nutrition, and so
on.

Hippocrates (b. 460 bc) of Cos in Asia
Minor, is better
known.
He was an Asclepiad -- i.e. a member of the medical guild, and is the
originator
of the Hippocratic Oath (click
here to read it. But note: Contrary to popular belief, few if any
doctors are required to take this or any other oath!). Despite
his background, he preferred to
avoid
mystical interpretations and stick close to the empirical
evidence.
For example, in a treatise called “On the sacred disease” (meaning
epilepsy),
he dismissed the usual demonic-possession theory and suggested that it
was an hereditary disease of the brain.

He is also known for his theory of humors. According to Greek
tradition, there are four basic substances: earth, water, air,
and
fire. Each of these has a corresponding “humor” or biological
liquid
in the body: black bile, phlegm, blood, and yellow bile, in that
order.

These humors, just like the four basic substances, vary along two
dimensions:
hot or cold, and wet or dry, like this...

wet

dry

hot

air/blood

fire/yellow bile

cold

water/phlegm

earth/black bile

Like Alcmaeon said, the task of the physician is to restore balance
when the relative proportions of these humors were out of
balance.
Hippocrates also noted some emotional connections to these humors.

It should be noted, despite the odd humor theory, that Hippocrates
and
with him Plato correctly recognized the significance of the
brain.
A bit later, around 280 bc, Erasistratus of Chios dissected the brain
and
differentiated the various parts.

For the most part, of course, medicine in these centuries, and for
many
centuries to come, consisted of a blend of first aid -- the setting of
bones, for example -- and herbal remedies, plus a considerable amount
of
praying to the gods for miraculous intervention! (For a brief
history
of psychopharmacology from ancient times to the present, click
here.)

In the Roman Empire, another physician gained
fame that would last
well
into the Middle Ages: Galen was born 130 ad in Pergamon
in
Asia Minor -- a major center of learning at the time. He went to
Alexandria -- THE center of learning -- to study anatomy. In the Roman
Empire, dissection of humans was not allowed -- based, of course, on
superstitious
fear of retribution, not on any feelings of human dignity! So
Galen
studied the great apes instead.

At the age of 28, he returned home for a while to serve as surgeon
to
the gladiators. His fame spread, and he went to Rome.

In addition to a great deal of fairly decent, concrete advice, he
theorized
that all life is based on pneuma or spirit. Plants had natural
spirit,
which causes growth. Animals have vital spirit, which is responsible
for
movement. And human beings have animal spirit -- from the word
anima,
meaning soul -- which is responsible for thought.

He believed that cerebrospinal fluid was the animal spirit, and
noted
that it was to be found in the cerebral vesicles of the brain as well
as
the spinal cord. He believed it traveled out through the nerves
to
the muscles, as well as in from the sensory organs. Not bad.

It was Galen who added the idea of temperaments to Hippocrates’ four
humors:

Blood

sanguine, cheerful

Phlegm

phlegmatic, sluggish

Yellow bile

choleric, angry

Black bile

melancholy, sad

Note how these words have come down to us. Note also how we
use
terms like “he is in a good humor,” “he has a bad temper” (as in
temperature), “he has a dry wit” (referring to the wet-dry dimension),
and "he is a hot-head" (the cool-warm dimension). Imbalances
among these psychological states, he believed, were one more cause for
diseases. Of course, this is the first known personality
typology!
It had some influence on people as varied as Alfred Adler, Ivan Pavlov,
and Hans Eysenck.

The rebirth of medicine

It is some time before we again see real progress in medicine and
physiology.
In 1316, Mondino de Luzzi came out with the first European
textbook
on anatomy, appropriately called Anatomia. Early
in
the 1500's, Da Vinci, naturally, plays a part with numerous
drawings
of skulls and brains, and even a wax casting of the ventricles.
In
1561, Gabriele Fallopio published Observationes Anatomicae,
wherein
he describes, among many other things, the cranial nerves and, of
course,
the fallopian tubes

Real progress had to wait for the invention of the microscope by Zacharias
Jansen of Middleburg, Holland, in 1595 (or by his father,
Hans).
It would be refined by Antonie van Leeuwenhoek in Holland, Galileo
in Italy and Robert Hooke in England.

(Soon afterwards, in 1608, a colleague of Zacharias Jansen in
Middleburg,
a German by the name of Hans Lippersberg, invented the telescope.)

Another major event was William Harvey’s (1578-1657)
explanation
of the circulation of the blood in 1628. Most physicians, still
using
Galen’s text, believed that the blood ebbed and flowed like a tide
through
the whole body!

Centers of medical education developed in the universities at Padua,
Italy and Leyden, Holland. Here, students studied anatomy, did
post-mortems,
and even dabbled in what we would now call pathology. They
performed
careful case-studies, with detailed measurements.

Neurophysiology developed in parallel to all the other medical and
physiological
developments. We could point to Thomas Willis’s
anatomical
description of the brain in 1664 as the first major step. His
book
was illustrated by Christopher Wren, the famous English artist and
architect.
Willis coined the term neurology in 1681.

A very significant contributor to the development of our
understanding
of the brain was none other than our old friend Rene Descartes.
He postulated a dualistic system, with a mind/soul interacting with the
brain/body by means of animal spirits (pneuma). The will (an
aspect
of our souls) enters the brain as animal spirits via the pineal gland,
interacts with the organization of nerves that represent established
habits,
courses through the nerves (viewed as tiny tubes) to the muscles,
causing
them to contract and so produce a behavior!

Likewise, actions upon the sensory neurons cause increases in
pressure
on the animal spirits, which course through the nerves to the brain,
influencing
the structure of the brain by repetition, as well as passing on to the
soul as perceptions.

Sometimes, the actions of the senses led to rather immediate
responses
by the muscles. These would be called reflexes by Descartes'
countryman,
Jean
Astruc, and were defined as cycles of action that do not require
the
intervention of the mind or soul. Descartes did include far more
complex behavior as reflexes than we would today.

Passions (roughly, emotions) also come from outside the body,
essentially
as sensations. They lead to a variety of physiological changes as
well as reflex actions: We see a bear, we run! In animals,
these passions are just sensations and reflexes. We, however,
experience
them with our mind/soul as wonder, love, hate, desire, joy, and
sadness,
as well as hundreds of combinations.

Descartes ideas, minus the soul, would be promoted by Julien
Offay
de la Mettrie (1709-1751) in a landmark book called Man a
Machine
(1748). Robert Whytt (1714-1766) would later lay down the
neurological basics of the reflex, and introduce the terms stimulus and
response. In 1791, Luigi Galvani cllinched these concepts
with his famous experiments involving the electrical stimulation of
frogs'
nerves.

About 1721, Lady Mary Montegu introduced a strange medical
practice
she had seen while visiting in Turkey: Inoculation. Instead
of letting a full-blown case of smallpox damage their lovely skin,
young
women had pus from someone with a mild case of smallpox injected just
under
the skin. (Don't laugh: Today, people have themselves injected
with
the poison botox to erase wrinkles!) Edward Jenner later
began inoculating
people against the smallpox by vaccinating them with cowpox
material.
The antibodies produced made one immune to smallpox as well as further
cases of cowpox.

The 1800's

Medicine got its greatest boost in
the 1800’s, especially after Louis
Pasteur (1822-1895) came up with the theory that diseases were
caused
by micro-organisms. The new field of bacteriology continued with
Pasteur’s friend Joseph Lister (1827-1912), who introduced the
novel
idea of antiseptic conditions in surgery -- especially washing one’s
hands!

Charles Bell (1774-1855) and François Magendie
(1783-1855) independently clarified the distinction between sensory and
motor nerves. They noted that sensory fibers enter the posterior
roots of the spinal cord, and motor fibers leave the anterior
roots.
Bell is also the first person to describe the facial paralysis we now
call
Bell's palsy. And Magendie was the first to test the cerebellum's
functions.

Franz Joseph Gall (1758-1828) of Vienna and, later, Paris,
studied
the shapes of skulls and concluded that the various bumps and
depressions
in each persons head related to certain psychological and personality
characteristics.
This would become very popular as phrenology, even though serious
scientists
such as Bell and Flourens thought it absurd. (For
a phrenological map of the head, click here. Please don't
misunderstand: There is little, if any, truth to this map!)

Marie-Jean-Pierre Flourens (1794-1867) concluded that the
cerebrum
was in fact responsible for thought and will, and that it operates
holistically
-- not as Gall would have it! He noted that the other parts --
cerebellum,
medulla, etc. -- had different functions, but that each also works
holistically
within itself. It is also Flourens who introduced ablation -- the
removal or destruction of particular parts of an animal's brain -- as a
way of
studying the connection between the brain and behavior.

However, things just never seem to be simple. Paul
Broca
(1824-1880), a French surgeon, had a patient that lost the power of
speech
due to a lesion in what is now called Broca’s Area. Another
surgeon,
Carl Wernicke, published a book
on aphasia in 1874. He, of course,
discovered the significance of Wernicke's area by doing an autopsy of a
patient who had lost the ability to comprehend
speech.

In 1870, two researchers, Eduard Fritsch and Gustav
Hitzig,
used direct electrical stimulation of the brain in a dog to discover,
among
other things, the motor and sensory cortices. Four years later, Robert
Bartholow did the same with a human brain. Their work
established that
there is indeed some localization of function -- it just doesn’t have
anything
to do with bumps on the head.

Johannes Müller (1801-1858), working in Berlin,
developed
the doctrine of specific energy of nerves. Each nerve, when
stimulated,
leads to only one sensory experience, even if it is stimulated in
another
manner than usual. A simple example is the light flashes you see
when you press against your eyeballs! This (I think
unfortunately)
led to increased belief in indirect realism -- i.e. that we don’t
actually
experience the world directly, much less accurately.

Hermann von Helmhotz

Hermann von Helmholtz is arguably the most famous German scientist
of
the 19th century. He was born in 1821 in Potsdam, Germany, to
Caroline
and August Helmholtz. His father, a teacher as well as an officer
in the Prussian army, began schooling young Hermann at home because of
health problems.

He did attend Gymnasium from the ages of nine to 17. He wanted
to study physics, but entered medical school in Berlin in 1838.
His
parents could not afford to send him without the scholarship given to
medical
students who promised to serve in the army after graduating.

Helmholtz befriended several other young men who were students of
Johannes
Müller at the nearby University of Berlin. Of these friends,
Emil Du Bois-Reymond went on to
discover the action potential, while
another, Ernst Brücke,
would have a certain Sigmund Freud as a
research assistant. These students of Müller,
in
contrast to their professor, swore a solemn oath to avoid vitalism, the
belief that there was something unique about living, as opposed to
non-living,
matter: “No other forces than common physical chemical ones are
active
within the organism.” Helmholtz adopted their position as well.

In 1842, he became an army surgeon at Potsdam, and continued
studying
math and physics on his own. In 1847, he read a paper at the Physical
Society
of Berlin on the conservation of energy. This alone would have
won
him an honored place in history!

Soon after, he became an associate professor of physiology at
Königsberg,
and married. During this period of his life, he measured the
speed
of the neural impulse. Prior, it was thought to be either
infinite
or the speed of light. He found it to be a paltry 90 feet per
second.
This put neurological activity well within the limits of ordinary
physical
and chemical sciences!

Along the way, in 1851, he invented the ophthalmascope -- the device
doctors use to look into your eye.

In 1855, he moved to Bonn to be professor of anatomy and
physiology.
Here he began his research into sight and hearing. In 1856, he
published
the first of three volumes called the Handbook of Physiological
Optics.

He moved once again in 1858, this time to Heidelberg as professor of
physiology. During this period, his wife died, and he later
married
a young socialite. His philosophical work focused on
epistemology,
and he continued his research on sight and hearing. His
explanation
of color vision -- that it is based on three cones sensitive to red,
green,
and violet -- is still remembered as the Young-Helmholtz theory.
He became quite famous.

In 1870, he was offered the chair in physics (his first love) at the
University of Berlin. In addition to a huge salary, he was
offered
living quarters and a new Institute of Physics.

He published a number of papers on geometry, especially the
non-Euclidean
kind that would be so important to people like Einstein in the
twentieth
century. His main focus was physics, of course, and one of his
prize
students was Heinrich Hertz, who was the first person to actually
generate
radio waves in 1888.

Helmholtz traveled to the US in 1893 as the German representative to
the Chicago Worlds Fair. A bad fall on ship put his health in
serious
jeopardy. He died of a cerebral hemorrhage in September of 1894.